Re: [PATCH v6] fbdev: fbmem: Fix the implicit type casting
From: Guenter Roeck <linux@roeck-us.net>
Date: 2022-02-03 01:07:43
Also in:
dri-devel, lkml
On Wed, Feb 02, 2022 at 03:58:09PM -0800, Yizhuo Zhai wrote:
In function do_fb_ioctl(), the "arg" is the type of unsigned long, and in "case FBIOBLANK:" this argument is casted into an int before passig to fb_blank(). In fb_blank(), the comparision if (blank > FB_BLANK_POWERDOWN) would be bypass if the original "arg" is a large number, which is possible because it comes from the user input. Fix this by adding the check before the function call. Signed-off-by: Yizhuo Zhai <redacted>
Reviewed-by: Guenter Roeck <linux@roeck-us.net> On a side note, change logs would be useful. Guenter
quoted hunk ↗ jump to hunk
--- drivers/video/fbdev/core/fbmem.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 0fa7ede94fa6..13083ad8d751 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c@@ -1160,6 +1160,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, ret = fbcon_set_con2fb_map_ioctl(argp); break; case FBIOBLANK: + if (arg > FB_BLANK_POWERDOWN) + return -EINVAL; console_lock(); lock_fb_info(info); ret = fb_blank(info, arg);-- 2.25.1